The present invention relates to flow measurement and more particularly to measurement of fluid flows with suspended solid particles, an area of measurement now served by triboelectric instruments. These comprise probes or rings in or around the flowstream coupled to a high gain current amplifier and measuring means. The triboelectric interactions with the probe generate currents on the order of 10.sup.-10 to 10.sup.-14 amperes.
Some triboelectric systems can be vulnerable to confusion engendered by probe contamination, battery effects, noise problems of the instrument and/or the flow system measured, long averaging times to factor out noise effects and/or the high impedance of the feedback resistors associated with their high current gain amplifiers. The high impedance aggravates probe contamination vulnerability. Measured triboelectric currents are integrals of charge transfer,--a phenomenon occuring at uncertain rates in many industrial systems to be measured.
It is the object of the present invention to provide an electrical (non-optical, non-radioactive, non-magnetic or Hall Effect based) flow measuring system which can be used for characterization of a flow of suspended solid particles in a flow (liquid or gas)--i.e., characterization of the flow velocity, mass flow particle concentration and/or relative proportions of mixed particle species, in a manner overcoming one or more, preferrably all, of the above problems.